Reference
The Tithis
A tithi is the time the Moon takes to gain twelve degrees on the Sun — so it is not a day, and it rarely lines up with one. Fourteen names repeat in both fortnights; the fifteenth is Purnima when the Moon is full and Amavasya when it is new.
Pratipada
प्रतिपदाThe first tithi. Beginnings are favoured, but the tithi is weak — pair it with a strong nakshatra.
Dwitiya
द्वितीयाFoundations, construction and anything meant to last are begun here.
Tritiya
तृतीयाSacred to Gauri; the Shukla Tritiya of Vaishakha is Akshaya Tritiya, an unbroken muhurat.
Chaturthi
चतुर्थीA Rikta tithi, yet sacred to Ganesha — good for worship and obstacle-removal, poor for new work.
Panchami
पञ्चमीLearning, medicine and the acquisition of skill. Vasant Panchami and Naga Panchami fall here.
Shashthi
षष्ठीSacred to Kartikeya. Chhath Puja is the Shukla Shashthi of Kartika.
Saptami
सप्तमीSacred to the Sun. Travel, movement and vehicles are favoured.
Ashtami
अष्टमीSacred to Shiva and to Durga. Krishna Janmashtami is the Krishna Ashtami of Bhadrapada.
Navami
नवमीA Rikta tithi, but the great Navami of Chaitra is Rama Navami — festival worship overrides the group.
Dashami
दशमीFull and stable. Vijayadashami is the Shukla Dashami of Ashwin.
Ekadashi
एकादशीThe fasting tithi, observed twice a month by Vaishnavas. Twenty-four in an ordinary year, twenty-six in an adhika-masa year.
Dwadashi
द्वादशीThe Ekadashi fast is broken in the Parana window of this tithi, which is time-bound.
Trayodashi
त्रयोदशीPradosh Vrat falls on this tithi twice a month, in the twilight window after sunset.
Chaturdashi
चतुर्दशीMasik Shivaratri falls on the Krishna Chaturdashi; the Phalguna one is Maha Shivaratri.
Purnima
पूर्णिमाThe full moon, and the close of the waxing fortnight. In the purnimanta reckoning the month ends here.
Amavasya
अमावस्याThe new moon, sacred to the ancestors. In the amanta reckoning the month ends here.
The five groups
Nanda, Bhadra, Jaya, Rikta, Purna
The classification repeats every five tithis and is what actually decides what a tithi is for. The Rikta tithis — the 4th, 9th and 14th — are the ones every muhurat text tells you to avoid.
Nanda
नन्दाJoyful — tithis of celebration and delight.
Suits: Festivals, celebrations, buying ornaments, music and the arts, auspicious beginnings.
Avoid: Nothing in particular; the weakest of the five only for grave, serious undertakings.
Bhadra
भद्राProsperous — tithis of growth and wellbeing.
Suits: Marriage, travel, opening a business, laying foundations, medical treatment.
Avoid: Confrontation and litigation.
Jaya
जयाVictorious — tithis of contest and conquest.
Suits: Court cases, competitions, examinations, negotiations, anything adversarial.
Avoid: Gentle or conciliatory work; peace-making.
Rikta
रिक्ताEmpty — tithis that drain what is begun in them.
Suits: Demolition, ending things deliberately, confronting enemies, debt recovery.
Avoid: All auspicious work — marriage, housewarming, naming, new ventures, journeys.
Purna
पूर्णाFull — tithis of completion and abundance.
Suits: Every auspicious work; completing what is already under way; ceremonies.
Avoid: Nothing in particular; the strongest of the five.
To see which tithi is running right now, and exactly when it ends, check today's panchang.